This invention relates to an improved process for phosphate beneficiation. In particular, this invention relates to the use of a condensate of a fatty acid or ester, an ethanolamine and a hydroxyethylethylenediamine as a collector for the flotation of siliceous matter from phosphate.
Typically, in the commercial beneficiation of siliceous phosphate ores, a deslimed and sized phosphate ore is conditioned with and then floated by a fatty acid collector and fuel oil reagent in an aerated aqueous solution at a pH of at least about 8. This flotation process produces a low-grade phosphate concentrate containing from about 50 to 65 weight percent bone phosphate of lime (BPL). The low-grade concentrate from the aforementioned flotation is blunged with acid to remove fatty acid collector coatings and the phosphate is further concentrated by flotation of residual silica from the concentrate with a so-called cationic amine collector.
U.S. Pat. No. 2,173,909 teaches the use of condensation products of alkanolamines and higher organic acids in a froth flotation process to float silica from phosphate. However, in the present commercial beneficiation of siliceous phosphate ores the reaction product of a polyalkylene polyamine and a fatty acid ester, as disclosed in U.S. Pat. No. 2,278,060, is generally employed as the cationic amine collector because of its relatively greater activity. These prior art cationic amine collectors are only moderately effective and selective. Furthermore, these collectors have become increasingly expensive in recent years.
U.S. Pat. No. 2,206,928 discloses the preparation of condensation products of hydroxyalkyl amines bearing at least two amino nitrogen atoms with higher organic acid substances. These products are disclosed to be useful as dispersing agents, wetting agents and the like. Nothing in this reference suggests that these condensation products are useful as flotation agents.